Mosasaurs of Sweden

(Webmasters Note: Mosasaurs were very successful marine predators that inhabited all the oceans of the Earth during the late Cretaceous period. One of the most unusual places that I have heard of their remains being found, however, is in southeastern Sweden. Johan Lindgren recently completed his Master's Degree at Lund University in Sweden and was kind enough to send me a copy of his thesis on Swedish mosasaurs. He studied mosasaur remains (primarily teeth and vertebrae) from late Cretaceous deposits in Sweden and has added significantly to the body of knowledge regarding these fascinating marine reptiles. The abstract of his thesis is included below. If you have questions regarding Swedish mosasaurs, you can contact Johan HERE.

Lindgren, J., 1998, Early Campanian mosasaurs (Reptilia; Mosasauridae) from the Kristianstad Basin, southern Sweden, Examensarbete i geologi vid Lunds Universitet, 20 poang, Nr 95, pp. 1-25.

Abstract: Marine strata of latest early Campanian age from the Kristianstad Basin in Skäne, southern Sweden, have yielded a diverse mosasaur fauna comprising four taxa: Clidastes cf. propython, Platecarpus sp., Hainosaurus ivoensis and Mosasauridae sp. The material consists primarily of isolated tooth-crowns, although a number of incomplete vertebrae and cranial elements have been recorded as well.

Based on the collections of mosasaur remains from four localities, i.e. Asen, Ignaberga, Maltesholm and Ugnsmunnarna, some differences in the distribution of mosasaur taxa within the Kristianstad Basin have been observed. Clidastes cf. propython is the predominant mosasaur in the near-shore deposits at Asen, whereas the Ugnsmunnarna site, with a more open water environment, has yielded mainly Platecarpus sp.

The assemblage is similar in composition to approximately coeval mosasaur faunas in the Upper Chalk Deposits in Norfolk, Sussex and Hampshire, England, the Lower Pierre Shale in South Dakota, USA and the Pembina Member of the Pierre Shale in Manitoba, Canada.

Hainosaurus ivoensis was formerly believed to be a species of Mosasaurus (i.e. M.cf. hoffmanni, M. hoffmanni ivoensis and M. ivoensis of previous writers.) Tooth crowns of Mosasauridae sp. are fairly large, strongly recurved and covered by smooth enamel. As this combination appears to be unique, Mosasauridae sp. may represent a new genus.

Johan has given me permission to put some of his illustrations, including his original mosasaur art work, up on this Oceans of Kansas Paleontology webpage. All images are Copyright ©1998 by Johan Lindgren and may not be used in any form without his permission:

	A map of southern Sweden (A) showing the location of the Kristianstad Basin in the north-eastern corner of Skäne and a close-up map (B) of the Kristianstad Basin with the localities yielding mosasaur remains marked. (Redrawn from Eristrom and Gabrielson, 1992)
	This is a schematic drawing of a mosasaurian skull (Plioplatecarpus sp.) in lateral view showing the marginal dentition (based on Holmes, 1996). The material available for Johan to study was made up primarily of teeth and isolated vertebrae.
	Restoration of Clidastes cf. propython in pursuit of small fish. Note the proportionally long body and short tail (based on Russell, 1967). In most other mosasaurs, the tail is almost half the length of the body.
	Restoration of Platecarpus sp. feeding on squid. (based on Russell, 1967). According to Russell (1970), Platecarpus may have favored cooler waters where belemnites were found in abundance.
	Restoration of Hainosaurus ivoensis attacking a Clidastes cf. propython mosasaur. Note the size differences between these two adult mosasaurs. From preserved stomach contents found in the U.S.A., we know that some species, including Tylosaurus, occasionally preyed on other mosasaurs.
	Besides the remains of their own Swedish mosasaurs, one Swedish Museum in Uppsala has a couple of mosasaurs from the Kansas chalk, including the type specimen of Halisaurus sternbergi. There is some question regarding the affinity of this specimen.

Johan and his 'supervisor', Dr. Mikael Siverson from the University of Lund, in Sweden, visited me in August, 1999. While in Kansas, Johan found his first mosasaur from the Smoky Hill Chalk. Although the remains were fragmentary, we believe that they were from a mosasaur called Platecarpus planifrons.